BACKGROUND ART The concept of tubular track for railways was first mooted in my RSA Patent No.

97/11696. The concept comprises the steps of preparing longitudinal trenches for the rails and then laying flexible tubes in the trenches followed to filling these tubes with concrete.

The resulting structure accepts the feet of the rails and suitable pads or the like may be used to dampen the forces on the concrete-filled tubes.

The tubular track concept provides full and continuous support below the rails, resulting in lower stresses and possible smaller rail size. There is also a fixed geometry with a resultant reduction in maintenance. In addition, the steel components for holding the gauge and also the rail to the tubes are formed around the tubes as opposed to being cast into a beam. The total structure is flexible and eliminates the normal shear forces created when cast in concrete. All forces created by trains are transferred to the tubes in compression which is the desirable situation for concrete.

While the system of laying the tubular track as described in the patent is satisfactory, it has been realised that it would be convenient if the time taken for the assembling and construction is shortened. Thus, one of the major time-taking steps is the curing of the concrete and also the logistics of construction including the transport of heavy machinery for filling the tubes with concrete.

It is an object of the present invention to provide a method and integers for effecting time saving and therefore reducing the costs for construction and reconstruction.

Another object of the present invention is to improve the compressive strength of the tubular track DISCLOSURE OF THE INVENTION According to the invention a method of forming tubular track includes the steps of filling short open lengths of tubular material with a settable composition, allowing the composition to set, in a predetermined shape or configuration, closing the lengths and inverting them for use as panels for laying tubular track The concept of the invention has been derived from the observation that the top zone of cured concrete has a very low compression strength whereas the middle and lower zones have far greater strength.

In a preferred form of the invention the short lengths of tubular material may be laid in a former of the desired curvature or shape and the edges thereof provided with means to fasten them together when the concrete or other settable composition has set. Thus the edges may be provided with hooks and loops type of connection.

In an example of the invention, the short lengths are formed as above, but the last filling before complete closing of the short lengths includes a final pumping of concrete.

In operation the short lengths are located in position and adjustments are made in relation to their location, height and the like and then fixing them in position and locating rails thereon.

The invention also extends to such short lengths of tubular structure which are preferably provided in pairs of the correct gauge.

These short lengths may be easily transported to the required work site without the rails, and stacked in layers; after which they can be laid end to end in pre-prepared trenches or like formations.

After this the correct alignment can be achieved, firstly by lifting and aligning the lengths and filling the gap between the trench or any formations in the trench, and the bottom of the lengths with a coarse material such as sand. Then the final alignment can be achieved by filling the remaining gap with fibre reinforced concrete of other durable material which should also have resilient properties.

If required, another final alignment may be accomplished by using the original tubular track concept-for example by placing a tube or bag in the gap and pumping it full of concrete or other suitable material to take up the shape of the gap.

The individual lengths may have protruding reinforcing and the adjacent reinforcing may overlap. This may be joined using the original method of using a bag and filling it with concrete or the like.

The individual lengths may also be designed to interlock to form a continuous support for the rails.

The individual lengths may also include hoops or straps to assist in retaining the shape or configuration. These hoops also serve to accept the transverse forces which occur during use.

It will be appreciated that if there is any subsidence or settlement of the soil, some panels may be lifted, filler material; from under the element being removed, the elements being returned to their desired position and the gap filled with aggregate. In the event that elements need to be replaced because of damage the same operation may be carried out.

BRIEF DESCRIPTION OF THE DRA WINGS An embodiment of the invention is described below with reference to the accompanying drawings, in which: Figure 1 is a cross section view of tubular elements in their final position;

Figure 2 is a similar view of a tubular element showing the formers used to shape the tubular elements; Figure 3 is a sectional view of an arrangement for forming the tubular elements and showing the inversion operation; Figure 4 is a sectional view of tubular track where the beam is formed to fill the gap between the bottom of the rails and the soil formation therebelow; and Figure 5 is a similar view but showing the filling of the gap between the bottom of the rails and the soil formation therebelow.

BEST MODE FOR CARRYING OUT THE INVENTION Referring first to Figures 1 and 2, formers 10 are shown which receive and retain a length of a tubular member for supporting a rail. This member takes the form of an elongated bag 11 of flexible material which has been filled with concrete. Suitable transverse (12) and longitudinal (13) reinforcing rods are provided.

The formers 10 are designed to correspond with the desired shape of the tubular element, which as shown in Figure 1 comprises connecting means 14, for example hooks and loops attachment (such as Velcro Trade Mark). The rails 17 are secured by means of clips 16.

In Figure 1 the formers 10 have been removed and the parallel tracks are joined by means of ties 15.

Referring now to Figure 3 the length of material 11 is located in the shuttering 19 which is positioned to achieve a particular cross sectional shape of the element and is held in place by toggle clamps. Concrete is applied either by being pumped in from a side or end or poured from a top position as indicated by-x-until full when the tubular element is formed by closing the connections means 14. As mentioned above a final filling operation is carried out before the final connection is made. The aggregate is then allowed to set and is then inverted and then placed in position using suitable guide means to assure correct

geometry. These latter means are shown as reference 22 which is an I-beam and 23 which is guide member. The rails 17 are shown in dotted line.

It will be appreciated that the inversion results in the bottom surface of the element to be straight and smooth, while the top surface may be irregular because it becomes the bottom surface in use. Thus the former 24 which is applied by press screws 25 may include a grid pattern, which also serves to improve traction with the earth base.

In Figure 4 the tubular element is located in hoops 27 and which have rail clips 16.

The tubular element rests on a layer 28 of soil. Backfill 29 is applied and a layer 30 of concrete is formed between the members. This layer may comprise a drain.

In Figure 5 the tubular members are located as shown but with the gap between the bottom of the tubular elements and the surface 31 of the soil being filled with a filler material 32.